On 6/25/2020 7:49 PM, Vivien Didelot wrote: > Hi Olivier, > > On Thu, 25 Jun 2020 18:35:32 +0200, Olivier Matz <olivier.m...@6wind.com> > wrote: >> As said by Ferruh, the unit of timestamp in mbuf is not normalized to >> nanosecs, as seen in rte_mbuf_core.h: >> >> /** Valid if PKT_RX_TIMESTAMP is set. The unit and time reference >> * are not normalized but are always the same for a given port. >> * Some devices allow to query rte_eth_read_clock that will return the >> * current device timestamp. >> */ >> uint64_t timestamp; >> >> Using the timestamp generated from a port which is not a pmd-pcap would >> require a conversion, using rte_eth_read_clock() on mbuf->port (assuming >> it was not modified, which should be true except if event eth Tx adapter >> is used). >> >> Also, note that the timestamp corresponds to the Rx timestamp. I think it >> could be an issue in case the mbuf is reassembled by the application: the >> timestamp in reassembled mbuf would be the one from the first fragment. >> >> So, I share Ferruh's concerns. > > I think this is not totally true depending on the driver. For instance, we > use mlx5 which already provides a timestamp conversion to nanosecs through > libibverbs. Let me resend this patch alongside Patrick's mlx5 patches that > implemented the needed glue, so that you may understand better the big picture > of how we enabled hardware timestamping in PCAP capture using mlx5 and pdump. >
Hi Vivien, Not sure a specific driver doing the conversion solves the issue. The check is to 'PKT_RX_TIMESTAMP' which is generic.
